Development of new neurologic studies requires thorough historic and methodologic reviews of prior investigations. These yield important unexplored etiologic clues that may be investigated using current technology. Major emphasis has been given to cerebrovascular disease, otitis media, inherited ataxias, Huntington's disease, febrile seizures, Tourette's syndrome, peripheral neuropathy, neurologic disease in the elderly, controlled thereapeutic trials of motor neuron disease, epilepsy, descriptive, analytic, and experimental methods in neuroepidemiology, statistical methods for calculating confidence intervals, and procedures for neuroepidemiologic investigations in developing countries.